Boletim da Sociedade Astronômica Brasileira, 32, no. 1, 62-63 c  SAB 2020 The origin of high-metallicity structures in the core of the Fornax galaxy group Hugo Vicente Capelato, Tatiana Ferraz Laganá, & Davi Dias Barbosa 1 Núcleo de Astrofisica Teórica, Universidade Cidade de São Paulo e Universidade Cruzeiro do Sul, São Paulo, Brazil e-mail: hugo.capelato@cruzeirodosul.edu.br e-mail: tatiana.lagana@cruzeirodosul.edu.br e-mail: davidiasbass@hotmail.com Abstract. We discuss the correlations between intra-group gas temperature and metallicity maps obtained from X-ray observations collected by the XMM-Newton observatory. Resumo. Discutimos as correlações entre mapas de temperatura e metalicidade do gás intra-grupo obtidos a partir de observações em raios-X coletadas pelo observatório XMM-Newton. Keywords. Galaxies: groups: individual: Fornax – Galaxies: clusters: intracluster medium – X-rays: galaxies: clusters 1. Introduction The Fornax group is the second most massive galaxy concentra- tion within 20 Mpc after the Virgo cluster. Most of the bright (m B < 15 m ) cluster members in the core are early-type galaxies, including the brightest active galaxy NGC 1399 (z = 0.0478). The Fornax cluster hosts a large population of dwarf galaxies and ultra compact galaxies as well a population of globular clus- ters and planetary nebulae (e.g. D’Abrusco et al. 2016; McNeil- Moylan et al. 2012). Intra-cluster light has been also detected in the core of Fornax (e.g. Iodice et al 2018). There are sugges- tions that the mass assembly of this group is still ongoing (e.g. Drinkwater et al., 2001). 2. Methodology Using data collected by the XMM-Newton observatory we ob- tained 2D maps of temperatures and metallicities (n Fe /n Fe ⊙ ) in the core region of Fornax. These 2D maps were made in a grid, where each pixel is 512 x 512 XMM EPIC physical pixels, so that each cell grid is 25.6 arcsec x 25.6 arcsec (1.3 h −1 70 Kpc at z = 0.0478) . In each pixel we performed a simultaneous spectral fit to determine the temperature and metallicity (Laganá et al., 2015). The results are shown in Figure 1 below. In order to understand the origin of the patchy distribution of temperatures and metallicities seen in Figure 1, we analyzed the local correlations between temperatures and metallicities aim- ing to find the signatures of processes proposed to explain the observed enrichment in the ICM: ram-pressure stripping (RPS, Gunn & Gott 1972), galactic winds ( De Young 1978), galaxy- galaxy interactions (Gnedin 1998), AGN outflows (De Young 1986) and intracluster supernovae (Gerhard+ 2002). Numerical simulations (e,g Kapferer et al. 2007, Ruggiero & Lima Neto, 2017) suggest that in the central dense regions of galaxy clusters - the case here - RPS is the dominant process given the higher density of the IG gas and the fact that galaxies velocities are higher in the clusters centers. For the same reasons we should expect a suppression of galactic winds in the center of clusters. As discussed by Lovisari et al (2011) because gas lost by galax- ies are generally colder and more metal rich than the IG gas, RPS processes should leave local characteristic signatures ex- pressed by anti-correlations between local metallicities and tem- Figure 1. upper left panel XMM map of the X-ray emission in the central region of Fornax. Most of the emission in concen- trated around the central galaxies NGC1399 and NGC1404. up- per right panel Color coded map of the temperature (keV) of the intra-group gas in the central region of Fornax; the inset shows the histogram of pixel values of this map. lower panel The same as for the upper panel but for the gas metallicities as given by the Fe abundance (Fe ˆ = n Fe /n Fe ⊙ ). The purple circles represent the galaxies belonging to the group with radius propor- tional to their B-magnitude (data from the HyperLeda database: http://leda.univ-lyon1.fr). Crosses are galaxies without measured m B . The central galaxy is NGC1399. The southern- most galaxy is the NGC1404. peratures occurring along the trails of galaxies being stripped. Another possibility is that of enhanced star formation in the tail of stripped gas. These star may evolve rapidly and explode as